Manufacture of odorless and odorstable mineral oil



Nav. 27, 1956 s. SCHNEIDER MANUFACTURE OF ODORLESS AND ODOR-STABLE MINERAL OIL Filed March 2, 1953 United States Patent O MANUFACTURE F ODORLESS AND DDOR- STABLE MINERAL OIL Sidney Schneider, Cranford, N. J., assigner to Esso Research and Engineering Company, a corporation of Delaware Application March 2, 1953, Serial No. 339,597

Claims. (Cl. 260--683.4)

The present invention concerns the manufacture of odorless and odor-stable mineral oils from the products derived from alkylating low-boiling isoparafns with low- Iboiling oleiins. It relates to a method of providing odorless and odor-stable mixtures of highly branched hydrocarbons that are especially adapted for use as ingredients in insecticides, paints, varnishes and the like. It particularly concerns mineral oil fractions derived from conventional alkylation processes that boil below about 550 F. and that are rendered odor-free and odor-stable by a sequence o'f acidtreating and alcohol-washing steps. It especially concerns one such fraction boiling in the range between about 330 F. and 400 F. and a second such fraction boiling in the range between about 400 yF. and 500 F. It also especially concerns a mineral oil that provides insecticides with improved insecticidal ability.

Recently, a great deal of `effort has been expended by the petroleum industry in the development of mineral oils that are odorless, odor-stable and suitable for use Ias ingredients in productsV such as paints, insecticides, and the like. The mineral oils employed in these products generally serve as solvents for the other ingredients contained therein. In the case of insecticides, however, it is particularly desired that the mineral oil itself contribute toward the insecticidal quality of the final product. In the case of both insecticides and paints, it is eminently desirable that the products be substantially free of obt jectionable odors and that they be odor-stable.

Accordingly, it is an object of the present invention to provide mineral oil fractions that are substantially free of any objectionable odor, -that are odor-stable, and that are adapted for use as ingredients in paints and insecticides. It is an additional object of the present invention to provide a mineral oil for use in conventional insecticides that will enhance their insecticidal qualities.

To achieve these objectives, the present invention utilizes two mineral oil fractions from the hydrocarbon products that are conventionally produced by alkylating low-boiling isoparafinic hydrocarbons with low-boiling olenic hydrocarbons. The isoparatiins generally employed in conventional alkylation processes include isofbutane and isopentane, while the oleiins generally employed are the C2C5 oleiins. Especially preferred reactants for the purposes of the present invention are isobutane and the Ci oleiins.

It will be noted that the hydrocarbon products normally desired fromA the alkylation of lo=w-boiling isopara'lns and oleiins are those boiling within the avia tion gasoline boiling range. The present invention, however, is primarily concerned 'with those hydrocarbon products that boil above the aviation gasoline range. Specifically, the present invention is concerned with the products that boil within the range between about 330 F. and 550 F., and especially those boiling within the range between about 330 F. and 500 F. A iirst fraction boiling Ibetween about 330 F. `and 400 F. is especially desired as an ingredient for paints, while a second fraction boiling between about 400 F. and 500 F. is especially desired as an ingredient for insecticides.

ICC

The process of the present invention is best carried out when the alkylation products falling within the range between about 330 F. and 500 F. are iirst separated from the total product of an alkylation reaction. The fractions boiling from about 330 F. to 400 F. and from about 400 F. to 500 F. may be treated individually or in admixt'ure. For the purposes of the present description, it will be considered that these tJWo fractions are treated separately.

In accordance with the process of the present invention the two alkylate fractions described above are subjected to a sequence of treating and washing steps. The rnost important steps in this sequence comprise one or more treatment `with concentrated sulfuric acid and one or more washings with aqueous alcohol. The sulfuric acid may range in strength between labout sulfuric acid land 25% oleum. It is preferred that the sulfuric acid have a strength between about 102% and 107%.

The hydrocarbon fractions may be treated with about 8 to 20 Vol. percent of sulfuric acid .at temperatures of about 30 C. to 60 C. and for periods from about 1/2 to 2 hours duration.

The hydrocarbon fractions may be washed by utilizing about 50 to 100 volpercent of aqueous alcohol at about 60 to 70 F. for contact periods of about l Iminute to 2 hours duration. The preferred alcohols include ethyl alcohol, n-propyl alcohol and isopropyl alcohol. lsopropyl alcohol is especially desired. The actual aqueous wash solution may contain about 30 to 60 vol. percent and preferably about 50 vol. percent of alcohol with the remaining part in each case being water. A small amount of an alkali may also 'be incorporated within the wash solution to render it slightly alkaline, e.. g., with `a pH of between about 7 and 8.. The alkali may be selected from the canbonates, bicarbonates and hydroxides of the alkali metals and especially sodium.A

It will be noted that ksulfuric 'acid treatments and aqueous alcohol iwashes are both conventionally employed in the reiining of the so-called white oils that are derived from petroleum crude o-il. It -will also be noted that the operating conditions thatA are employed in .these white oil relining steps are very similar to the ones employed in the process of the present invention. The particular combination process, however, employing both sulfuric acid treatments Aand aqueous alcohol washes is employed only in the rening off the heavy white oils that boil well above the two alkylate fractions with 'which the present invention is concerned. Furthermore, Iwhen white oils that correspond in boiling range to the present fractions are subjected to both sulfuric acid and aqueous alcohol treatments, the products that are thereby produced are still not satisfactory insofar as their odor characteristics are concerned.

The success of the present process in deodorizing and stabilizing selected alkylate fractions and its failure to perform likewise on white oils of equivalent boiling point ranges may be due to several factors. For example, it will be noted that the alkylate fractions are derived from feed stocks .that are virtually aliphatic in structure, while the white oils are derived from crude oil frac- `tions that contain both aromatic and naphthenic as Well as aliphatic hydrocarbons. This difference in the chemical composition may possibly be an important factor.

ln the refining -o-f White oils, the sulfuric acid treatments serve primarily to remove aromatic compounds and compounds that :contain sulfur from the start-ing crude Ioil fractions. In the refining of high-boiling white oils, Ithe sulfuric acid treatments resul-t rin the production 4of substantial yamounts of sulfonic acids that are convetted 'to soaps by subsequent treatmentV with :an alkali. The soaps are then recovered by one or more Washing steps employing aqueous alcohol as the washing medium.

In :the refining of white oils that boil in the same range as the two alkylate fractions of interest in the present invention, it is accepted practice to use the saine sulfuric acid treating steps that are employed in the lrefining of lthe high-boiling white oils. rIlhe aqueous alcohol washing steps, however, are not used since the production of sulfonic :acid soaps in Vthe case of the low-'boiling fractions is negligible. The production of `sulfonic acid soaps is likewise negligible in the case of the two `alkylate fracftions of interest in the present invention. Hence, the prior art does not indicate that alcohol washing steps lwould be beneficial in `treating the latter fractions.

lIt is of interest to note that relatively l-ow-boiling white oils have been generally accepted as :a suitable ingredient for use in insecticides land especially in household insecticides. Particularly desirable for this purpose have been the white oil-s .that iboil in range of about 400 to 500 F. and that possess a color of yat least .about 25 Saybolt, a sulfur content of the order Iof 0.02 wt. percent or less, an .ani-line point in excess of about 170 F., and an acceptable odor.

The odor of a white oil is conventionally evaluated in the following manner. A sample of the oil is :sniffed at room temperature by an odor committee having a minimum of three persons, and the sample is rated as: (l) Pass, (2) acceptable, yor (3) does not pass.

This test is admittedly subject -to variations inthe odor perception of the individuals. For this reason, the individuals are `specially trained for this work, and the atmosphere in the test area is kept as odor-free as possible. The :three odor ratings are arrived at Iby conducting surveys among consumers; land the overall test has proven to be :a reasonably `accurate one for the purpose.

Unfortunately, in the case of those white oils that boil in the range of about 330-500 F., it is diilicult lto provide products that possess completely satisfactory odor and odor-stability characteristics. It is particularly difficult to produ-ce oils that are free of 'a kerosene odor; :and it is practically impossible to impart good odor-stability to the oils.

Numerous refining procedures have been attempted on conventional lowboiling white oils in :an effort to improve their odor and odor-stability, ibut little or no :success has been realized. The procedures employed, have included extensive extraction with solvents such as phenol and alcohol, treatments with sulfuric acid, vacuum fractionation, and filtration through clay, activated carbon, silica Igel, and other Iadsorbents. None of 'these techniques, however, lhas provided a solution to .the odor problem. Masking perfumes have lbeen considered, rbut the concentrati-ons required for the purpose have proven to be excessive and the masking .odors themselves are often undesirable.

'It has now been found, however, that odor-free :and odordstable hydrocarbon ingredients for insecticides, paints and the like may be obtained by employing the lalkylate fractions a-nd the processing steps of the present invention, This invention may be more easily understood by reference to the attached figure depicting one embodiment of the same.

In the :attached figure, an olefin such as a mixture of Ibutenes flows through line 2 and is mixed with :an isoparain such as isobutane in line 1. The resulting mixture flows into alkyl-ation zone 3 where it is contacted with lan .-alkylation catalyst such as sulfuric or hydroftuoric .acid in .a conventional manner .to produce what is comm-only referred to :as a bu-tene alkylate of isobutane. Conventional reaction conditions generally call for the use of an isobutane/olefin m-ol ratio `of about 3/1 or more, .about 60-70 vol. percent of acid catalyst lbased on the reaction mixture, and an acid purity of at least 90% and preferably at least 98%. The reaction temperature is generally about 40 to 50 F. for sulfuric acid and about 75 to 100 F. for hydrouoiic acid.

The resulting product mixture flows through line 4 into settling zone `5 where it separates into an acid layer and -a hydrocarbon layer. The acid is conventionally recycled .through line 7 :to :alkylation zone 3, while the ihydrocarbon layer flows th-rough line 6 to caustic washing zone 8. Here the latter layer is contacted with an alkali to neutralize lany acidic components, such as sulfur dioxide, which are formed in small quantities by catalyst degeneration.

The caustic washed hydrocarbon product then flows through line 9 into distillation zone l10 which in actual practice generally consists of a deis-obutanizer, a debutanizer, a rerun -tower and a depropanizer.

Isobutane is removed from distillation zone 10 through line 11 .and may be returned Ito alkylation zone 3. A normal butane cut may be withdrawn through line 12 and an laviation alkylate fraction boiling up to about 330 or 360 F. through l1i-ne13.

The first alkylate fraction of the present invention, boiling within the range of about 330 tto 400 F. may be withdrawn through line 40; while .the second alkylate fraction of the present invention may be withdrawn through line 14. It will be appreciated that both of these streams are treated in substantially lthe same manner and hence maybe processed :as one combined stre-am. In that cas-e the two fractions may be separated after passage through the sequence of processing steps ,about to be described. `For the purposes of Ithe present description, however, it will be lassumed that these ltwo fractions aJre separately handled throughout.

A bottoms fraction is withdrawn from zone 10 via line 41. This fraction may -be utilized in any convenient manner.

The alkylate fraction in line 14, boiling within the range of about`400-550 F. :and preferably 400-500 F., flows to acid treating zone .115 where it is contacted with about 8 to 20 vol. percent of 98% sulfuric acid at a Vtemperature of Iabout 40 F. and for 1a period of about l hour. The resulting acid/oil emulsion flows through line 16 .to settling zone 17 where an acid layer and an acid/.oil layer :are formed. The spent acid is withdrawn through line 19 and the acid/ oil layer through line 18.

It will be noted that treating zone 15 and settling zone 17 may actually be -t-he same physical structure, but .they are preferably separate vessels. In addition, these zones as well as the various other treating zones may be of `such `a character to provide leither continu-ous or batchtype ope-ration.

The `acid/ oil in line 18 may be repeatedly acid ltreated and settled as by passage through zones 20 land 22 land line 21. The conditions employed in these zones may be maintained substantially the same fas in zones 15 and 17.

The acid-treated alkylate leaving the last settling zone (e. g. zone 22) passes through line 24 into neutralization zone 25, where it is neutralized by treatment with an alkali. The alkali may be a carbonate, bicarbonate or hydroxide of any of the alkali metals in aqueous solution. It is preferably about a 20% solution of sodium carbonate in water. f

The neutralized alkylate then flows through line 2 into alcohol washing zone 27 where it is contacted with about vol. percent of an aqueous solution of an alcohol. As stated earlier, the solution preferred for use in this zone is a 50-50 mixture of water andisopropyl alcohol.

The alcohol washing is carried out at about 60-70 C. and preferably for a period of time between l and 60 minutes. The mixture produced in zone 27 passes through line 28 and separates into an aqueous alcohol layer and an alkylate layer. The spent alcohol is withdrawn through line 30 while the alkylate passes out through line 31.

The alcohol washing operation in zone 27 may be repeated in zone 32 and the resulting mixture Settled white oil samples were determined immediately after the rening steps and again after storing the samples in diffused light for different periods of time. The results of this series of experiments are presented in the two settling zones have been shown in the attached 5 following table:

Table I Feed Stock Alkylate White Oil Total Olcum Treat, Vol. Percent. 12 l2 Treating Scheme T-T-W 1 T-T-W 1 Water Wash Yes Yes No Yes..- No. Alcohol Wash. N N N0 Yes. Clay Filter. Yes No Yes. Yes. Odor Borderline Borderline Acceptable DNP DNP D N P.

Accepta- Accepta ble. ble. Odor after 3 Days (2) DNP 2. DNP Acceptable-. DNP DNP DN P. Odor` after7Days (2) DNP DNP Acceptable- DNP. DNP. DNP. Odor after 10 Days (2) DNP DNP. Acceptable-. DNP DNP DNP.

l Treating scheme consisted of 2 successive 6 vol. percent treatments with 25% oleum followed by a washing step employing either Water or aqueous alcohol as the wash solution.

2 Did not pass.

figure and are the preferred number of zones to be em- It is apparent from the data presented in the above ployed. The number of such zones, however, may vary table that the alkylate feed stock and the processing from l to 4 or more of each type. Further, the zones may be operated either batch-wise or continuously, and the settling zones may be integral with or separate from the Washing zones.

The Washed alkylate product in line 37 may contain a small amount of moisture which may be easily removed by air-blowing the alkylate at a temperature of about 100-ll0 C, or more. Alternatively, dry steam may be blown through the alkylate at a temperature of about 120 C. or more. When the alkylate is recooled to about atmospheric temperature, any water contained therein forms a separate layer which may be easily withdrawn from the alkylate. This procedure is a conventional one throughout the petroleum industry for removing water from hydrocarbon fractions.

If the resulting alkylate has an unsatisfactory color, this property may be easily improved by contacting the alkylate with Attapulgus clay, as for example by percolating it through the clay. This adsorbent is preferred over either activated carbon or silica gel, since the latter two adsorbents have been found to have an adverse effect on the odor and odor-stability of the alkylate. The operating conditions commonly employed in contacting conventional white oils With a color adsorbent have been found to be satisfactory 4in the present process.

EXAMPLE l In order to more clearly demonstrate the present invention, a sample of an alkylate fraction boiling in the range of 400 to 500 F. was given two successive treats with a total of l2 vol. percent of 25% oleum and was then neutralized with a sodium carbonate solution in a conventional manner. The resulting neutral oil or alkylate was then alcohol washed with two 100 vol. percent treats of a 50% isopropyl alcohol solution in water and then filtered through paper. The odor 0f the resulting alkylate product was then determined immediately after this treatment and again after storing the alkylate in diffused light for different periods of time. Duplicate samples of the alkylate were subjected to the same acid treating and caustic neutralization steps, but these samples were not washed with alcohol. Instead, both of the samples were washed with water, and one of the samples was then passed through a lter bed composed of Attapulgus clay.

As a basis for comparison, three samples of a conventional white oil having a boiling range of 400 to 500 F. were processed in the same manner as the three samples of alkylate described above. As in the case of the alkylate samples, the odor and odor-stability of the steps of the present invention make possible the manufacture of a hydrocarbon product that possesses a satisfactory odor and odor-stability. It is also apparent that the choice of feed stock and refining procedure is critical in that only one feed stock and only one sequence of treating steps are capable of producing the desired results.

The criticality insofar as the choice of feed stock is concerned is readily apparent when one compares the three runs made on the alkylate fraction with the three runs made on the conventional white oil fraction. It will be noted that all three of the alkylate products possessed an odor that was either borderline acceptable or completely acceptable, while none of the white oil samples had a satisfactory odor. The criticality insofar as the choice of processing steps is concerned is aptly demonstrated by the fact that only the sequence advocated by the present invention was capable of producing a mineral oil fraction that possessed a satisfactory odorstability as Well as a satisfactory odor.

It will be realized that many variations and combinations of the processing steps advocated by the present invention may be utilized without departing from the spirit or scope of the invention. For example, the feed gases to the alkylation zone may be actual refinery gas streams containing conventional amounts of isobutane, normal butenes, propylene and so forth. In the alkylation zone itself, a wide range of operating variables may be employed including the use of many conventional types of mixers, acid strengths, acid concentrations, proportions of reactants and so forth. Again, the alkylation, settling and caustic washing zones may be either separate physical entities or merely one vessel used for all three purposes.

In a similar manner, the distillation zone employed to fractionate the alkylation product from the alkylation zone may consist of one or a plurality of fractionating towers, columns, and so forth. As pointed out earlier, the alkylate fractions of the present invention, e. g., the 330-400 F. fraction and the 400-500 F. fraction, may be withdrawn from the distillation zone as one fraction or as two separate fractions. In the former instance, the two fractions may be acid treated and alcohol washed in unison and then the fractions separated in a subsequent fractionation zone. In the latter instance, the two fractions may be treated as described earlier herein. As was also pointed out earlier in this description, the acid treating steps, the settling steps, neutralization steps and so forth, may be carried out in the same reaction or treating vessel, but it is preferred that separate vessels be employed. Likewise, it is preferred that the present process be carried out on a continuous basis rather than batch-Wise.

A second feature of the present invention lies in the fact that the deodorized and odor-stable alkylate fraction boiling between about 400 F. and 500 F., which is produced by the present treating process, is especially adapted for use as an ingredient in insecticides. In this connection, this particular alkylate fraction may be used in combination with conventional insecticides including pyrethrum, rotenone, nicotine, lead arsenate, di-p-chlorophenyl-trichloroethane and so forth. It is particularly desired that the alkylate fraction be used in combination with about 3 to 7 wt. percent and especially about 5 wt. percent of DDT. Also-particularly desirable are insecticide compositions comprising the alkylate fraction and about 0.01 to 1.0 wt. percent and especially about 0.1 wt. percent of pyrethrins.

It will lbe noted that it may be desirable to incorporate emulsifying agents within the alkylate along with a conventional insecticide when the mixture of alkylate and insecticide is to be used as an emulsion concentrate for aqueous spraying. Suitable emulsifying agents include various soaps, such as sodium resinate, sodium oleate, fatty acid esters, sulfonated and sulfated preparations, and the like.

It will also be noted that other constituents such as white oils, kerosenes, and the like that are conventionally employed as vehicles for insecticides may be incorporated in the compositions of the present invention. It is preferred, however, that these constituents not be used due to their odor characteristics.

EXAMPLE 2 In order to demonstrate the manner in which the 400 to 500 F. alkylate fraction of the present invention enhances the insecticidal quality of a conventional insecticide with which it may be used, data were obtained comparing insecticide compositions made from this alkylate fraction as well as a conventional mineral white oil. The alkylate fraction employed in this instance was prepared in accordance with the process of the present invention and possessed the following physical properties:

Specic gravity 0.7805 Color, Saybolt +30 Flash, Pensky-Martin 175 F. Pour point, F Less than -90 F. Aniline point 193.5 F. Sulfur content, wt. percent 0.011

The conventional mineral oil solvent with which the above alkylate fraction was compared was a white oil fraction boiling in the range of about 400 to 500 F. and was a sample of an oil that is conventionally employed as a solvent for household insecticides. In one instance, the solvents under test were mixed with 0.1 wt. percent of pyrethrins, and the resulting mixtures were then evaluated on household flies and roaches using a standard procedure (the Peet-Grady method) for this purpose. Similar tests were carried out with compositions containing about wt. percent of DDT and 15% of an aromatic solvent having a gravity of 30.7 API and a boiling range of 318 to 338 F. The results of these tests are given in the following table:

Table Il COMPARISON OF KNOOK DOWN PERFORMANCE OF ALKYLATE AND WHITE OIL IN INSECTICIDES From the data above, it is apparent that the deodorizedl alkylate product of the present invention is more effective than the conventional white oils that are employed in the formulation of insecticides. From'the standpoint 5 of odor, the alkylate-containing formulations are far superior to the conventional White oils.

The alkylate fraction boiling within the range of about 330 to 400 F. and prepared in accordance with the present process possesses the same odor superiority Vover comparable white oil fractions as does the alkylate product boiling within 400 to 550 F. The production of the former fraction may be achieved in substantially the same manner as the higher-boiling material.

While the two alkylate fractions described above are the two most desired products, it will be noted that any fraction boiling somewhere Within the range of 330 to 550 F. may be prepared.

What is claimed is:

l. Process of manufacturing substantially odorless and odor-stable mineral oils which comprises alkylating a low-boiling isoparain hydrocarbon with a low-boiling olefin hydrocarbon, fractionating the resulting alkylate into a plurality of fractions including a fraction boiling within the range of about 330 F. to 550 F., acid-treating said fraction with concentrated sulfuric acid, neutralizing the acid-treated fraction with an alkali, and washing the neutralized fraction with an aqueous aliphatic alcohol.

2. Process as defined in claim 1 in which the isoparain hydrocarbon contains from 4 to 5 carbon atoms and the olen hydrocarbon contains from 2 to 5 carbon atoms.

3. Process as defined in claim 1 in which the isoparaflin is isobutane and the olefin contains 4 carbon atoms.

4. Process of manufacturing an odorless and odor stable mineral oil which comprises alkylating isobutane and an oleiin hydrocarbon containing about 4 carbon atoms, segregating a fraction of the resulting alkylate that boils within the range of about 330 F. to'550 F., treating said fraction with concentrated sulfuric acid, neutralizing the acid-treated fraction with an alkali, and washing the neutralized fraction with an aqueous aliphatic alcohol. 45 5. Process as defined in claim 4 in which the acidtreated fraction is treated with an aqueous sodium carbonate solution to neutralize any acidic constituents prior to the washing step.

6. Process as defined in claim 4 in which the aliphatic alcohol contains from 2 to 3 carbon atoms.

7. Process as dened in claim 4 in which the aliphatic alcohol is isopropyl alcohol.

8. Process as defined in claim 7 in which the alkylate fraction boils within the range of about 330 to 400 F. 55 9. Process as deiined in claim 7 in which the alkylate fraction boils within the range of about 400 to 500 F.

10. Process as defined in claim 1 in which the alcoholwashed fraction is contacted with Attapulgus clay.

References Cited in the tile of this patent OTHER REFERENCES Chemical Rening of Petroleum, Kalichevsky, The Chemical Catalog Co., New York, N. Y., 1933. Pages 28-29, 246-247 relied on.

Ginsburg, Journ. of Econ. Ent., vol. 28, February 1935, pages 237 and 239 t0 242. 

1. PROCESS OF MANUFACTURING SUBSTANTIALLY ODORLESS AND ODOR-STABLE MINERAL OILS WHICH COMPRISES ALKYLATING A LOW-BOILING ISOPARAFFIN HYDROCARBON WITH A LOW-BOILING OLEFIN HYDROCARBON, FRACTIONATING THE RESULTING ALKYLATE INTO A PLURALITY OF FRACTIONS INCLUDING A FRACTION BOILING WITHIN THE RANGE OF ABOUT 330* F. TO 550* F., ACID-TREATING SAID FRACTION WITH CONCENTRATED SULFURIC ACID, NEUTRALIZING THE ACID-TREATED FRACTION WITH AN ALKALI, AND WASHING THE NEUTRALIZED FRACTION WITH AN AQUEOUS ALIPHATIC ALCOHOL. 